Vehicles which may be rail bound, road bound or both may perform construction or maintenance work along a railway are known today. Often the vehicles include at least four wheels for rail transportation and some sort of hydraulic driving unit.
DE-A1-102005002407 describes such a vehicle, with four wheels and at least one hydraulic motor. it also describes that the hydraulic motor connected to a wheel is connected in series to an other hydraulic motor connected to the other wheel of the same side so that the front wheel and the rear wheel of the left side is connected together by their hydraulic motors. One drawback with this execution is that when the user does construction or maintenance work on the side of the rail while moving the vehicle forward or backward the wheels may start to slip, whereby the traction force decreases. The vehicle has a bad differential effect which affects the wheels of the vehicle when e.g. the vehicle perform work along the side of the rail while driving in curves.